This project aims to provide detailed experimental information on the mechanisms and dynamics of protein folding and assembly at the level of peptide fragments. High resolution two-dimensional NMR spectroscopy will be used to investigate the intrinsic folding tendencies of peptide fragments of proteins and to elucidate the factors which lead to their stabilization and assembly into folded protein structures. Previous work has identified incipient secondary structure in peptide fragments derived from influenza virus hemagglutinin (reverse turn) and myohemerythrin (helix). In the present project we will study the influence of amino acid sequence on the stability of the secondary structures in these and other peptides and investigate their folding and stabilization through interactions at the surface of a fully folded carrier protein, bovine pancreatic trypsin inhibitor (BPTI). Each peptide can be coupled at four discrete sites on BPTI giving four different 1:1 peptide: BPTI complexes. This allows us to investigate the influence of several different protein surfaces on the folding of each peptide. NMR techniques will also be used to study the folding and assembly into enzymatically active complexes of peptide fragments of thioredoxin obtained by CNBr and tryptic cleavage.